How to determine if an array is empty in php

3 judgment methods: 1. Use count() or sizeof() to calculate the length of the array and determine whether the length of the array is 0. The syntax is "count(array)==0". If it is 0, it is empty. Array, otherwise it is not an empty array. 2. Use empty() to check whether the array variable is empty. The syntax is "empty (array)". If TRUE is returned, it is an empty array. 3. Use the "===" operator to determine whether the array is "[]", the syntax is "array ===[]", if TRUE is returned, it is an empty array, otherwise it is not an empty array.

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

php determines an array Several methods to determine whether it is an empty array

Method 1: Use count() or sizeof() function

An array with a length of 0 We call it an "empty array". An empty array is a real object that only contains 0 elements.

Therefore, we can use the count() function to calculate the length of the array, and then determine whether the length is 0; if it is 0, it is an empty array, otherwise it is not an empty array.

count($arr,$m)

$m: is an optional parameter and can be omitted.

• If the $m parameter is omitted, or set to COUNT_NORMAL or 0, the count() function will not detect multidimensional arrays;

• If If $m is set to COUNT_RECURSIVE or 1, the count() function will recursively calculate the number of elements in the array, which is especially useful for calculating the number of elements in multi-dimensional arrays.

<?php  
header("content-type:text/html;charset=utf-8");
// 声明一个空数组
$empty_array = array(); 
   
// 检查数组是否为空
if(count($empty_array) == 0) 
    echo "数组为空"; 
else
    echo "数组不为空"; 
?>

The sizeof() function is an alias of the count() function, that is, the function and usage of the sizeof() function are the same as The count() function is exactly the same.

<?php  
header("content-type:text/html;charset=utf-8");
// 声明一个空数组
$empty_array = array(); 
   
if( sizeof($empty_array) == 0 ) 
    echo "数组为空"; 
else
    echo "数组不空"; 
?>

Method 2: Use the empty() function

The empty() function is used to check whether a variable is empty.

empty() Determines whether a variable is considered empty. When a variable does not exist, or its value is equal to FALSE, then it is considered not to exist. empty() does not generate a warning if the variable does not exist.

Note: Any uninitialized variable, a variable with a value of 0 or false or an empty string "" or null, an empty array, or an object without any attributes will be judged as empty==true

Returns FALSE when the variable exists and is a non-empty and non-zero value, otherwise returns TRUE.

<?php  
header("content-type:text/html;charset=utf-8");
// 声明一个空数组
$array = []; 
   
// 检查数组是否为空
if(empty($array)) 
    echo "数组为空"; 
else
    echo "数组不为空"; 
?>

If the detected array is:

$array = [1,2,3];

Method 3: Use "===" Determine whether the array is "[]"

• If TRUE is returned, it is an empty array

• If FALSE is returned, it is not Empty array

<?php  
header("content-type:text/html;charset=utf-8");
// 声明一个空数组
$array = array(); ; 
   
// 检查数组是否为空
if($array===[]) 
    echo "数组为空"; 
else
    echo "数组不为空"; 
?>

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